Many operators of modern hydraulic cranes were trained on mechanical cranes. The operating techniques for mechanical cranes are not directly transferable to todays modern hydraulic cranes. In the hoisting operation, mechanical crane operators have always been taught to idle the engine and engage the control as fast as possible to avoid slipping the clutch. At the same time, the operator used the accelerator to vary the hoist speed. The technique required on hydraulic cranes is different from that required on mechanical cranes. On the hydraulic crane the operator keeps the engine at a high idle and varies the hoist speed by moving the control lever from its normal, neutral, position to a pressurizing position.
There are two problems related to rapid movement of a hoist control lever on a hydraulic crane. The first type of problem arises when the operator lowers an empty hook or crown block. If the operator moves the control lever too fast, the hoist drum accelerates faster than the wire rope can be pulled off the drum by the weight of the empty hook, ball or crown block. If the operator suddenly stops the downward motion by returning the control lever to its neutral position, the excess wire already fed off the hoist drum tends to whip. The whipping action tends to force the wire rope to jump to the next layer or groove on the hoist drum. As a result, the wire rope wears quickly. In contradistinction, when the operator handles a heavy load, rapid movement of the hoist control lever results in a sudden pressure buildup in the hydraulic system. The tie-down bolts securing the hydraulic pumps and motors are heavily stressed as a result of the sudden pressure buildup in the hydraulic system. In addition, the mechanical drive train components are also stressed as a result of the sudden acceleration of the hoist drum.